PROJECT ABSTRACT The International Immunocompromised Host Society (ICHS) will host the 21st International Symposium on Infections in the Immunocompromised Host on June 7-9, 2020 in Melbourne, Australia. This one-of-a-kind symposium brings together clinicians, researchers, and industry leaders to discuss and critically examine the latest findings relevant to people who are immunocompromised?a rapidly growing population. Numerous threats, such as emerging pathogens as well as the increase in drug-resistant bacteria and viruses, pose unique challenges for this population. Clinicians must be informed of the latest advances to provide the best care for these patients, and researchers need to be up-to-date on the current breakthroughs to develop new diagnostics, prevention strategies, and treatments. The 21st ICHS Symposium conveys the key significant discoveries and disseminates this vital knowledge to participants who research and treat diseases in immunocompromised patients. Some of the highlights from the program include industry-sponsored symposia, plenary lectures, ?Meet the Professors? workshops, a ?Best Abstracts? symposium, a ?Top Five Papers? symposium, and an interactive ?Stump the Professor? workshop. Examples of topics to be covered include updates on challenges in solid organ transplants, tropical diseases, the role of the microbiome, current treatments for fungal infections, recent advances in treating viral infections, and personalized genomic medicine. The presenters are a mix of leaders in their field as well as new investigators who are generating exciting results. One of the main goals of the ICHS Symposium is to highlight the accomplishments of new investigators and bring their research to a global audience to ensure that the field continues to benefit from the next generation of researchers and clinicians. The influence of the ICHS Symposia also extends beyond the meeting. Past symposia have stimulated updates on clinical guidelines and resulted in comprehensive reviews published in high-impact journals where they reach a broad audience. The 21st ICHS promises to be an engaging meeting that will facilitate future advances in a wide range of fields relevant to the study and care of the immunocompromised host.